Manic depressive illness, known in medical communities as bipolar illness, is the most distinct and dramatic of the depressive or affective disorders. Unlike major depression, which occurs at any age, manic-depressive illness generally strikes before the age of 30. Almost 2 million Americans suffer from bipolar illness.
The distinction between bipolar illness and other depressive disorders is that patients swing from depression to mania, generally with periods of normal moods in between the two extremes. Some patients, however, cycle from mania to depression and back within a few days and without a period of normal mood. People with this condition are called rapid cyclers.
Though manic-depressive disorder can become disabling, it also is among the most treatable of the mental illnesses. The combination of psychotherapy and medications returns the vast majority of manic-depressive patients to functioning lives.
The most common medication, lithium carbonate, successfully reduces the number and intensity of manic episodes for a majority of those who take the medication. Twenty percent become completely free of symptoms. Those who respond to lithium best are patients who have a family history of depressive illness and who have periods of relatively normal mood between their manic depressive phases.
Very effective in treating the manic phase, lithium also appears to prevent repeated episodes of depression. One theory for this is that in controlling the mania, lithium helps prevent the swing into depression.
Lithium works by bringing various neurotransmitters in the brain into balance. Scientists think the medication may affect the way or the speed at which the brain cells break down the neurotransmitters that are thought to control moods.
However, like all medications, lithium can have side effects and must be very closely monitored by a psychiatrist. The doctor should measure the level of lithium in the patient's blood as well as how well the patient's kidneys and thyroid gland are working. Among the side effects are weight gain, excessive thirst and urination, stomach and intestinal irritation, hand tremors, and muscular weakness. More serious side effects are hypothyroidism, kidney damage, confusion, delirium, serious seizures, coma and, in patients who are not closely monitored by a physician, even death.
The amount of lithium needed to treat or prevent manic and depressive symptoms effectively differs greatly from one patient to another. The doctor determines how much lithium a patient needs by taking a sample of blood from time to time. The blood is analyzed to determine how much lithium is present. Testing for the lithium blood level is a vital part of treatment with lithium. It aids the doctor in selecting and maintaining the most effective dose. Just as important, lithium blood levels assure the doctor that a patient is not taking a toxic dose-that is, a poisonous dose. Lithium is an unusual drug because the amount needed to be effective is only slightly less than the amount that is toxic. For that reason, patients must be very careful not to take more lithium than prescribed. Lithium levels in the blood can change even when the patient takes the same dose every day: The concentration of lithium can increase when a person becomes ill with another medical condition, especially influenza or other illnesses that result in fever or changes in diet and loss of body fluids. Surgery, strenuous exercise, and crash diets are other circumstances that can lead to dangerously increased lithium levels in the blood. The doctor should be informed of illness or changes in eating habits, and a regular blood testing schedule should be set up and followed rigorously. If a patient stops taking lithium for only one day, the blood level of the drug falls to half that needed for effective therapy. A forgotten dose should not, however, be taken with the regular dose the next day, because it could raise the lithium level too much. Furthermore, the lower lithium level that results from missing one dose is unlikely to jeopardize therapeutic response. Because the blood level of lithium rises rapidly for a few hours after swallowing a lithium pill and then slowly levels off, having a blood test right after taking the drug can mislead the doctor into thinking that the dose is too high. To gauge the average blood level accurately, it is important to have blood drawn about 12 hours after the last dose of lithium. Otherwise, the results will be misleading and possibly dangerous. Most patients take their nighttime dose of lithium and then come to the doctor's office the next morning to have a blood test before taking their first dose for the day. Some patients are able to take their full daily dose at bedtime and do not have to worry about the morning dose when getting a blood level.
Lithium is excreted from the body almost entirely by the kidneys. If, for some reason, the kidneys are unable to get rid of the proper amount of lithium, the drug may accumulate to dangerous levels in the body. The excretion of lithium in the kidneys is closely linked to that of sodium. The less sodium, or salt, in the body, the less lithium is excreted, and the greater chance of lithium buildup to toxic levels. Diuretics cause the kidneys to excrete sodium; as a result, lithium levels rise. The reason that many illnesses can increase lithium levels is that increased sweating, fever, a low salt diet, vomiting, and diarrhea all result in less sodium present in the body, thus producing higher levels. Lithium should not be taken by patients with severely impaired kidney function. Patients with heart disease and others who have a significant change in sodium in their diet or periodic episodes of heavy sweating should be especially careful to have their lithium blood levels monitored regularly.
As explained above, lithium concentration in the blood needs to be carefully monitored. A novel, accurate and efficient optical sensor allowing a medical professional to monitor and regulate such lithium levels by accurately distinguishing between potassium, sodium and lithium ions would be an excellent tool for the treatment of diseases such as manic depressive illness.
As such, there is a need in the art for an efficient and reliable device and method capable of measuring lithium ion concentration of a biological fluid.